Application of biochar from crop residues for the removal of lead and copperJosé M. De la Rosa1, Águeda Sánchez-Martín1, María L. Sánchez-Martín1, Nikolas Hagemann2,3, Heike Knicker1, and Paloma Campos1*
(1) Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Reina Mercedes 10, 41012, Seville, Spain, (2) Agroscope Zurich, Reckenholzstr. 191, Zurich, Switzerland, (3) Ithaka Institute, Arbaz, Switzerland.
Acknowledgements:The former Spanish Ministry of Economy, Industry and Competitiveness (MINEICO) and AEI/FEDER are thanked for funding the projects CGL2016-76498-R and CGL2015-64811-P. MINEICO is also thanked for funding the “Ramón y Cajal” post-doctoral contract of José M. De la Rosa. P. Campos thanks the “Fundación Tatiana Pérez de Guzmán el Bueno” for funding her PhD.
Due to the chemical composition and surface properties of biochar, aC-rich porous material produced by pyrolysis of biomass, it can act asan effective tool for the remediation of soils polluted with traceelements [1, 2]. However, its capacity to sorb these contaminants in asolution varies considerably depend on pyrolysis conditions, but alsoon the feedstock. Biochar properties vary with feedstock, pyrolysistemperature and time of pyrolysis [3].
Objective: to evaluate the capacity of biochars from two crop residuesto sorb Pb2+ and Cu2+.
INTRODUCTION
MATERIALS AND METHODS
RESULTS
CONCLUSIONS
References:[1] Uchimiya, M.; Klasson, K.T.; Wartelle, L.H.; Lima, I.M.; 2011. Chemosphere 82, 1438-1447.[2] Zhao, J., Shen, X.-J., Domene, X., Alcañiz, J.-M., Liao, X., Palet, C., 2019. Sci. Rep. 9, 9869.[3] Campos, P., Miller, A.Z., Knicker, H., Costa-Pereira, Merino, A., De la Rosa, J.M., 2020. J. Waste Manag. 105, 256-267.
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% R
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Cu2+ concentration (mM)
% Removal of Cu2+ by biochars
2. Batch adsorption experiments
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• High SSA-BET was not related with high adsorption capacity of the biochars. It may
be more related to the total acidity.
• CWB, followed by RHB, showed the greatest capacity for adsorption of Cu2+ and Pb2+.
• OPB showed the greatest SSA-BET, whereas it also showed the lowest % of removal
for both cations. OPB showed few acid sites (only 0.17 meq g-1), related with low
oxygen content and very low O/Cat ratio.
• Langmuir model well fitted data of RHB and CWB, whereas Freundlich and Temkin
fitted better adsorption data in OPB.
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CWB
RHB
OPB
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O-H vibr.
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90
Aromatic C=C bendingAlkene C=C stretching
Aromatic C=C skeletal vibr.
96
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Si-O-Si vibr.C-O strectching vibr.Graphite
moietiesCO3
2- out-of-plane
C-H aromatic out of the plane
C-O-C skeletal vibr.Aliphatic C-H stretching
TC (%) TH (%) TN (%) O (%) H/Cat O/Cat C/NAsh content
(%)
CWB 75.7± 0.3 1.80±0.02 0.30± 0.06 18.7 0.3 0.19 252 3.5 ± 0.7
RHB 53.7±0.1 1.61±0.02 0.51±0.24 9.48 0.4 0.13 106 34.7 ± 0.5
OPB 92.7±0.2 2.52±0.06 0.16±0.09 3.58 0.3 0.03 585 1.0 ± 0.3
pH WHC (%)SSA-BET (CO2,
m2 g-1)Iodine Index
Total basicity (meq g-1)
Total acidity (meq g-1)
CWB 9.95 ± 0.18 243 ± 39 403 149 0.95 1.69
RHB 10.10 ± 0.01 595 ± 22 292 180 0.51 1.70
OPB 9.34 ± 0.09 70 ± 13 473 123 0.05 0.17
1. Biochar characterization
Table 2. Physical and chemical characteristics and Surface properties of biochars.
Table 1. Elemental analysis and ash content (%) of biochars.
RHB
-1000100200300ppm
Alkyl
O/N Alkyl
Aryl
Carboxyl/amide
OPB* *
a) b)
c) d)
Figure 2. % of removal of Cu2+ and Pb2+ by biochars (a and b) and capacity of adsorbents (c and d).
Figure 1. 13C-NMR (a) and FT-IR (b) spectra of the studied biochars. (*) Spinning size bands.
b)a)
• TC > 50 % for all biochars. Biochars showed high aromaticity.
• Greater SSA-BET measured with CO2 for OPB and CWB than RHB.
• Greater basic and acid sites for RHB and CWB than OPB.
• % Removal of the studied cations in the following order: CWB>RHB>OPB.
• Langmuir isotherm fitted well for RHB and CWB for both cations.• Temkin and Freundlich fitted Cu2+ and Pb2+ adsorption for OPB, respectively.
Continuously feed reactorPyreka reactor500 °C12 min N2 flux
Certified wood biocharproduced by Swiss Biochar620 °C20 min No inert gas
Rice husk
(RHB)Olive pit
(OPB)
Wood chips (CWB)
• Elemental composition• pH, Water Holding Capacity (WHC)• SSA-BET, iodine number, total acid and basid sites• FT-IR, 13C-NMR
Biochar20 mg
20 mL 48 h, 25 rpm
Centrifugation & filtration (0.45 µm)
ICP-OESSupernatant
Initial conc. Cu2+/Pb2+:
0.05, 0.1, 0.5, 1, 2 and 5 mM
OPBRHB CWB
CWB
